Many operations in a subterranean borehole involve the setting of took that are mounted outside of a tubular string. A common example is a packer or slips that can be used to seal an annular space or/and support a tubular string from another. Prior mechanical actuation techniques for such devices, which used applied or hydrostatic pressure to actuate a piston to drive slips up cones and compress sealing elements into a sealing position, involved openings in the tubular wall. These openings are considered potential leak paths that reduce reliability and are not desirable.
Alternative techniques were developed that accomplished the task of tool actuation without wall openings. These devices used annular fluid that was selectively admitted into the actuator tool housing and as a result of such fluid entry a reaction ensued that created pressure in the actuator housing to operate the tool. In one version the admission of water into a portion of the actuator allowed a material to be reacted to create hydrogen gas which was then used to drive a piston to set a tool such as a packer. Some examples of such tools that operate with the gas generation principle are U.S. Pat. No. 7,591,319 and US Publications 2007/0089911 and 2009/0038802.
These devices that had to generate pressure downhole were complicated and expensive. In some instances the available space was restricted for such devices limiting their feasibility. U.S. Pat. No. 8,813,857 shows an actuator that goes in the hole, with stored potential energy that employs a variety of signaling techniques from the surface to actuate the tool and release the setting pressure/force. The preferred potential energy source is compressed gas. This design incorporated a magnet dropped or pumped into the borehole that communicated with a valve to initialize the pressure generation step to actuate the tool due to valve operation. This design required multiple deliveries of wiper plugs with magnets for actuation of more than a single tool. In the case of a liner hanger and liner top packer that is to be set after a cement job with the liner hanger already set, the design in this reference would require multiple darts which creates some uncertainty that the darts would reach their destination and actuate the respective tools. The present invention delivers multiple tools that need to be set at different times with a running tool that contains the trigger for actuation so that in a single trip multiple tools can be set in one trip into the hole at different times without wall openings in the tubular. Those skilled in the art will further understand the invention from a review of the description of the preferred embodiment and the associated drawings while further appreciating that the full scope of the invention is to be determined by the appended claims.